Safety officials say that hundreds of deaths in airline crashes over the past five years are attributable to pilots who have become too dependent on computerized fight controls, forgetting how to react in certain situations.

Although fatal airline accidents have decreased dramatically over the past 10 years, the International Air Transport Association reports that some 51 “loss-of-control” accidents — in which planes stalled or got into unusual situations from which pilots were not able to recover — have occurred over the past five years, making it the most common type of airline accident.

In an extensive report, the Associated Press describes one such crash, which occurred near Buffalo, N.Y., in 2009. An investigation concluded that all 49 people aboard the Continental Airlines plane died because of pilot error:

“The co-pilot of a regional airliner programmed incorrect information into the plane’s computers, causing it to slow to an unsafe speed. That triggered a stall warning. The startled captain, who hadn’t noticed the plane had slowed too much, responded by repeatedly pulling back on the control yoke, overriding two safety systems, when the correct procedure was to push forward.

An investigation later found there were no mechanical or structural problems that would have prevented the plane from flying if the captain had responded correctly.”

The AP report adds that a draft FAA study — which examined 46 accidents and major incidents, 734 voluntary reports by pilots as well as data from more than 9,000 flights in which a safety official rides in the cockpit to observe pilots — found that pilots sometimes “abdicate too much responsibility to automated systems.”

The 2009 Air France crash that killed 228 people happened after the planes air sensors fed bad information to the plane’s computers, causing the aircraft to stall. A co-pilot tried to save the stalled plane but did not know how to properly do so. In July, French investigators — in response to those findings — recommended that all pilots get mandatory training in manual flying and handling high-altitude stalls.